Later Monday morning, the district sent the following e-mail to district parents:

"Early this morning, a photo that was taken last spring of some Baraboo School District students who appear to be making extremely inappropriate gestures began circulating on social media. The District has confirmed at this time that the photo was not taken on school property or at a school-sponsored event.

"The school district is investigating the situation and is working with parents, staff and local authorities. If the gesture is what it appears to be, the district will pursue any and all appropriate actions, including legal, to address the issues.

"With that, we want to be very clear: The Baraboo School district is a hate-free environment where all people, regardless of race, color, religion, creed, sex, sexual orientation, gender identity, national origin or ancestry, are respected and celebrated."

The note was signed by Superintendent Lori Mueller.

The photo appears to have been taken on the steps of the Sauk County Courthouse before last spring's prom.

The photo also drew a response from the Auschwitz Museum, which tweeted "It is so hard to find words...."

The museum added: "This is why every single day we work hard to educate. We need to explain what is the danger of hateful ideology rising. Auschwitz with its gas chambers was at the very end of the long process of normalizing and accommodating hatred."

It is so hard to find words...

This is why every single day we work hard to educate. We need to explain what is the danger of hateful ideology rising. Auschwitz with its gas chambers was at the very end of the long process of normalizing and accommodating hatred. https://t.co/13AzZaMGJR

"The actions displayed in this photo have no place in Wisconsin. As elected officials, we have a responsibility to lead by example for a generation growing up in a climate where they see this behavior condoned," Evers said. "I will be in contact with Baraboo officials, but we must all be clear: intolerance and bigotry must never be tolerated, in our schools or anywhere else."

Lt. Gov.-elect Mandela Barnes added that such actions would not be tolerated.

"Wish I was shocked, but the comfort they share in embracing supremacist culture is the most obscene part. This happens when the behavior is increasingly more excused and/or promoted," Barnes tweeted. "It cannot be tolerated, ignored, or inconsequential. This will not be us."

The Baraboo area is represented by State Sen. Jon Erpenbach (D-Middleton), who said he was appalled by the photo and wants to know more about how it came to be taken.

"I saw it and it's disgusting," he said. "There is absolutely no place in the world for something like that."

The Baraboo police department said in a Facebook post that it was aware of the photo controversy and officers are assisting the school district's investigation.

Patrick Marley and Mary Spicuzza of the Journal Sentinel contributed to this report.